I can't offhand find the thread in which this was discussed, but unless or until Zazzle makes your dream come true, you can do pseudo-transparency by placing a semi-transparent layer above the layer in question, the semi-transparent one created in your image editor. Admittedly, it isn't the same as what you're hoping for.
PDF and PNG support transparency, If created in programs like Photoshop and Gimp and uploaded to the Design Tool to be used as layers.
I don't know if the level of opacity will create opaque layers when printed.
Here's an example using a PNG layer, a semi-transparent square:
Here's the risk... The printer could print everything flat. I'm not sure which level of opacity works well (something like 30%, 40%... Maybe 50% opacity?)... If the layer is not transparent enough the printer could just print something like the image below (completely flat elements):
When I've played with semi-transparency, I've tried to use the highest transparency possible just in case the printing part of it ends up being too aggressive. So, 20-30%.
I've found this info about transparency in the Zazzle Design Tool:
"Supported Image Types
Zazzle supports images in JPEG, PNG, PDF, SVG and Adobe Illustrator (AI) formats. These formats will produce great quality products as long as the resolution meets or exceeds our recommendations. We support full transparency for PNG, PDF and AI files. This can be especially useful if you are creating a design with multiple overlapping images such as borders to go around your design, or shapes with non-rectangular edges. For PDF and AI formats, we support vector output for most of our products. Please note that within the Zazzle Design Tool, a rasterized (bitmap) version of your vector-file will appear."
I assume you mean opacity adjustments to make objects/layers more or less "transparent", such as texts, svgs, etc. Zazzle already tried this time ago with text if I remember right, but had to dismiss it again. I suppose due to printing issues that may occur. This is a common problem, that's why it is not recommended to use semitransparency/opacity functionality on vector-based graphic/print files.
PNG semitransparency is a different story. Since it is a raster image, it works well, except on specific print techniques, e.g. on DTG T-Shirt printing. In these cases, it is noted in the description.
So, use semitransparent PNG where wanted, this works also for (non-editable) text. For dynamic text that has to be changed within the designer, you have one trick you may use: Create 2 versions of your background image, one at full opacity saved as JPG or PNG, doesn't matter, the second one as transparent PNG with opacity set to let's say 50%. Within Z's designer, first add the regular image as background, then put your text template over it, and on the very top upload the semitransparent PNG-variant. Make sure both images are at the same size and place. The semitransparent PNG image will practically simulate a semitransparent effect on your text while not affecting the regular (same) image underneath. Play with the text coloration and the opacity value of your PNG image to make things look good.
@Fiorenzo, I still have a product on which I used the opacity adjustments on text templates. It was wonderful to work with, but my guess is that the problem with it might have been people using it who hadn't used it before in, say, an image editor, both designers and customers. I was so sorry when the ability was lost. However, the same effect is available with PNG images, but they can't be used for text templates. Bummer.
@Barbara I guess it was more of a technical problem. Transparency (opacity) of vector- and text-based elements in print files can lead to printing issues, this is well-known among graphic designers. Alpha transparency of PNG images is a whole different animal since they are raster/pixel-based.
You CAN simulate lesser opacity on dynamic text with the trick I mentioned. You only need a duplicate of the background image in a semi-transparent PNG format and use this as an overlay over your dynamic text template. Look at the marble texture showing over the year on the front page of my calendar - it's made this way:
@Fiorenzo, I've done that sort of thing, in particular for turning modern photos into simulations of Daguerreotypes where the photos are all templates. Let's see if I can find one...
Yes, the image in this one isn't a template, but it could have been:
I removed the image from a real Daguerreotype and used it as a layer above the image. It's the same idea as your marble overlay.
@Barbara I see you know the little tricks 🙂 Looks nice (and perfect). If you allow me a little critique: I would turn on editing for customers, so they can make further changes such as choosing a different font (wanted to check but turned off).
